1. Field of the Invention
The present invention relates to an externally pressurized gas bearing used as a thrust or journal bearing or the like.
2. Description of the Prior Art
In general, externally pressurized gas bearings have already been widely used practically, but all of these conventional ones premise that the gas flow within a bearing gap is a slow subsonic flow. The intra-bearing gap flow partially becomes a supersonic flow near the entrance of a gas supply hole, but a shock wave produced within the bearing gap causes the flow to become a subsonic flow at the outer edge of the gap. Consequently, as the supply gas pressure is increased, the load capacity and static rigidity take maximum values at a certain level of the supply gas pressure, and a further increase of the supply gas pressure results in a decrease of those values.
Then, after the supply gas pressure continues to increase until the shock wave reaches the outer edge of the bearing gap, a further increase thereof causes the load capacity and rigidity to increase again. In these conventional bearings, however, in order to realize a supersonic flow at the outer edge of the bearing gap, a several hundred atmospheric pressure is required as the supply gas pressure, and yet the load capacity and rigidity are limited. Static pressure gas bearings require only a small rotational torque and are therefore suitable for highspeed rotation, but are fundamentally disadvantageous in that the load capacity and rigidity cannot have large values for the above reason.